Precuring apparatus and method for reducing voltage required to electrostatically material to an arcuate surface

Abstract

A precurl device for adjusting the curvature of the paper prior to being disposed on a transfer drum (48). The paper is fed along a path defined by a guide (296) to a nip between two precurl rollers (244) and (246). The durometer of the roller (246) is higher than the durometer of the roller (244), such that the roller (244) will deform at the nip between the rollers. The paper is fed to an attachment roller (198) that is adjacent the drum (48). A variable precurl device (312) is operable to vary the force on the roller (244) against the roller (246), to vary the amount of arcuate deformation imparted to the paper (146).

What is claimed is: 
     
       1. A print engine paper feed device for feeding paper onto a rotating arcuate surface, comprising: a directing device for directing a sheet of paper along a defined path;   a precurl device for deforming said sheet of paper to have an arcuate deformation that allows said sheet of paper to follow an arcuate path in the direction of curvature of the rotating arcuate surface defined as a predetermined number of degrees of path curvature per path millimeter of travel that is greater than a predetermined minimum and a combined curl-droop angle greater than a predetermined minimum, said curl-droop angle defined as the sum of the angle of repose of said sheet of paper prior to deformation thereof over an unsupported fixed length and the angle of curl of said sheet of paper over a fixed length after deformation thereof;   a precurl control for controlling the amount of arcuate deformation imparted to said sheet of paper by said precurl device; and   an attachment device for attaching said sheet of paper to the rotating arcuate surface after arcuate deformation thereof by said precurl device.   
     
     
       2. The print engine paper feed device of claim 1, wherein the rotating arcuate surface has a predetermined curvature associated therewith and said arcuate deformation corresponds to the direction of curvature of the rotating arcuate surface. 
     
     
       3. The print engine paper feed device of claim 1, wherein said precurl device comprises: a first roller with a first durometer;   a second roller with a second durometer disposed adjacent said first roller to form a nip therebetween with a predetermined pressure between said first roller and said second roller at said nip and a predetermined nip angle theta;   the durometer of said first roller greater than the durometer of said second roller such that said second roller will be deformed at said nip; and   at least one of said second rollers being driven.   
     
     
       4. The print engine paper feed device of claim 3, wherein said precurl control comprises a variable pressure device for varying the predetermined pressure at said nip to define the deformation of said second roller with the paper disposed in said nip. 
     
     
       5. The print engine paper feed device of claim 1, wherein said first roller has substantially no deformation associated therewith due to the predetermined pressure at said nip. 
     
     
       6. The print engine paper feed device of claim 1 wherein said curl-droop angle is greater than 15°. 
     
     
       7. A method for feeding paper onto a rotating arcuate surface in a prim engine, comprising the steps of: directing a sheet of paper along a defined path;   deforming the sheet of paper to have an arcuate deformation that allows the sheet of paper to follow an arcuate path in the direction of curvature of the rotating arcuate surface defined as a predetermined number of degrees of path curvature per path millimeter of travel that is greater than a predetermined minimum and a combined curl-droop angle greater than a predetermined minimum, the curl-droop angle defined as the sum of the angle of repose of the sheet of paper prior to deformation thereof over an unsupported fixed length and the angle of curl of the sheet of paper over a fixed length after deformation thereof;   controlling the amount of arcuate deformation imparted to the sheet of paper in the step of deforming; and   attaching the paper to the rotating arcuate surface after arcuate deformation thereof by the step of deforming.   
     
     
       8. The method of claim 7, wherein the rotating arcuate surface has a predetermined curvature associated therewith in a predetermined direction and the step of deforming operable to impart an arcuate deformation to the paper that corresponds to the direction of curvature of the rotating arcuate surface. 
     
     
       9. The method of claim 7, wherein the step of deforming the sheet of paper comprises: providing a first roller with a first durometer;   providing a second roller with a second durometer;   disposing the first roller adjacent the second roller at a predetermined compression therebetween to form a nip therebetween, the nip disposed along the defined path and having a predetermined nip angle theta;   the durometer of the first roller greater than the durometer of the second roller such that the second roller will deform at the nip; and   driving at least one of the rollers.   
     
     
       10. The method of claim 9, wherein the step of controlling the amount of arcuate deformation provided by the step of deforming comprises supplying a variable pressure to at least one of the first and second rollers to vary pressure at the nip to define the deformation of the roller with the paper disposed at the nip. 
     
     
       11. The method of claim 9, wherein the first roller has substantially no deformation associated therewith due to the predetermined pressure at the nip. 
     
     
       12. A print engine paper feed device for feeding paper onto a rotating arcuate surface of radius R millimeters, comprising: a directing device for directing a sheet of paper along a defined path;   a precurl device for deforming said sheet of paper to have an arcuate deformation along an arcuate path that is equal to or exceeds 2.9 degrees of path curvature per path millimeter of paper travel;   an attachment device for attaching the paper to the rotating arcuate surface after arcuate deformation thereof by said precurl device.   
     
     
       13. A print engine paper feed device for feeding paper onto a rotating arcuate surface, comprising: a directing device for directing a sheet of paper along a defined path;   a precurl device for deforming said sheet of paper to have an arcuate deformation that allows said sheet of paper to follow an arcuate path in the direction of curvature of the rotating arcuate surface defined as a combined curl-droop angle greater than 15°, said curl-droop angle defined as the sum of the angle of repose of said sheet of paper prior to deformation thereof over an unsupported fixed length and the angle of curl of said sheet of paper over a fixed length after deformation thereof;   a precurl control for controlling the amount of arcuate deformation imparted to said sheet of paper by said precurl device; and   an attachment device for attaching said sheet of paper to the rotating arcuate surface after arcuate deformation thereof by said precurl device.